Australian news, and some related international items

Keep an eye out for China’s “out of control” Tiangong-1 space station

SCIENCE  It’s a long shot, but Chinese space station could fall to earth here , SMH, By Liam Mannix 30 March 2018 

If you get killed by the Chinese space station that’s due to fall out of the sky this weekend you’ll probably be remembered as having had one of the most unlikely deaths on record.  Your chances of being hit by Tiangong-1, China’s first space station, are about 10 million times smaller than your yearly chance of being struck by lightning.

But Melburnians would still be advised to watch the skies over the coming days, just in case, with much of Victoria inside a band where there’s a very slightly larger possibility of the debris hitting.

If you die, you would be the first known person ever to be killed by falling space debris. But maybe not the first animal; according to legend, when the remains of the American space station Skylab fell on outback Western Australia in 1979, it killed a rabbit.

“The chances of you being struck by this are essentially zero,” says Associate Professor Alan Duffy, an astronomer at Swinburne University  “An individual human is a tiny target relative to the Earth which itself is mostly water and even the land is mostly of sparsely populated regions.”

The station is as big as a bus and weighs several tonnes. Its name means “heavenly palace” in Chinese, but the space station has more in common with Icarus than any castle in the clouds, and is set for a fiery demise.

Estimates vary – some scientists have organised competitions to see who can most accurately predict when the station will hit the atmosphere – but most place its descent to earth in a window between midnight Saturday and early morning Monday.

Precise predictions about when the satellite will re-enter the atmosphere are very hard to make, requiring scientists to factor in the density of the atmosphere as well as the space station’s speed, orientation and physical properties.

Indeed, Tiangong’s re-entry will probably first be spotted by people staring up at the sky – hopefully with camera-phones ready.

The odds are, the space station will burn up in the atmosphere, with what is left falling in the oceans.

……..Satellites are typically “de-orbited” – deliberately dumped out of orbit – over water so they don’t pose a risk to people. But in 2016 China announced it had lost control of Tiangong-1. Since then, the station has been slowly orbiting closer and closer to Earth.

When it reaches a height of about 70 kilometres above the surface, the atmosphere will start to melt the station. It could take up to 20 minutes for the whole station to decompose.

If the space station does de-orbit over Australian skies, get ready for a hell of a lightshow. Burning pieces of the station will likely stay visible for a minute or more, making for great viewing if the day is clear, says Markus Dolensky, technical director at the International Centre for Radio Astronomy Research.

“We may potentially witness the end of Tiangong as a series of fireballs streaking across the sky,” he says.


March 31, 2018 - Posted by | General News

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